Project Summary Socioeconomic disparities in math skills have grown in recent years, as the math skills of children at the upper end of the income distribution have grown faster than those of children from middle- or low-income families (Reardon, 2011). SES gaps in math skills first emerge in preschool (Klibanoff, Levine, Huttenlocher, Vasilyeva, & Hedges, 2006; Stipek & Ryan, 1997) and are maintained as children progress through school (National Bureau of Economic Research, 2005). SES-related disparities in math skills are concerning to policy makers and educators alike because they have implications for long-term achievement and educational attainment in adulthood (Duncan et al. 2007; Ritchie & Bates, 2013). Thus, there is an urgent need to disentangle the mechanisms underlying SES disparities in math skills before children start kindergarten. This investigation aims to delineate the proximal experiences driving socioeconomic disparities in math skills in the home environment during early childhood. This study will address three aims using longitudinal, multimethod data on a socioeconomically diverse sample of 4-year-olds (N = 400) and their parents, including direct assessments, in-home observations, surveys, and time diaries. First it will examine associations between the home learning environment (HLE) and math skills at 4 and 5 years of age. Second, it will delineate SES disparities in HLE and their implications for math learning. Third, this study will be the first to test general and math-specific family stress and family culture as pathways through which SES shapes the HLE and early math skills. Results from the proposed work will offer critical insights into the development of SES disparities in math in early childhood. By delineating the importance of the home learning environment for SES disparities and how variations in family stress and family culture may be linked to SES, we will test and refine a clearly defined theoretical model derived from previous work in psychology and sociology. This knowledge will fill critical gaps in the extant literature and identify key targets for experimentally manipulated intervention and policy efforts which seek to improve the well-being of socioeconomically disadvantaged children.